Thermal mass heat storage.

[Dave Shepard]

Most commonly seen in masonry heaters. But is anyone using any other systems to store heat? I have a friend that helps me out with a lot of engineering projects, and questions related to most anything. His opinion on burning wood is to burn it hot, fast, and completely. This is how the masonry heaters work. Has anyone else tried any other methods, like heating water and storing it in a super insulated tank? I've seen many people running outdoor boilers very inefficiently, usually by burning low quality fuel at too low a temperature. A fast hot fire would really change the ability to cleanly and efficiently recover lower quality fuel, and not smudge out the neighborhood.


Dave

[Don_Papenburg]

I have been planning some sort of setup like that for my garage and house .  I was thinking a sand heat sink would work also.  When I get sand for blasting it will remain hot for a couple of days in an uninsulated tank .   Anouther way to do the thermal  storage is to have cement walls insulated well  on the outside (6" or more of good foam)

[Dave Shepard]

Burying a large tank in sand was one of the storage methods he mentioned. Would probably have to have it set up so that it was below frost or had some sort of anti freeze in it in case you weren't going to run it. I would use a water to water exchanger for this type of system.


Dave

[zopi]

Use barrels of water painted black to support tables in greenhouses..passive heat retention..

I'm wondering about using a ground source on the return side of a solar collector  with a simple fan/exchanger/thermostat to heat/cool a greenhouse..hmm..guess I need to do some reading..

[submarinesailor]

Have any of you looked into using Phase Change Materials like Glauber's Salt.  The salt changes from a solid to a liquid at about 90F, storing large amounts of heat.  Greater than that of water or rock.  The heat is released as it changes back to a solid.  Check out these links:
http://en.wikipedia.org/wiki/Phase_Change_Material
http://www.ces.purdue.edu/extmedia/AE/AE-89.html

Thermal storage
The high heat storage capacity in the phase change from solid to liquid, and the advantageous phase change temperature of 32 degrees Celsius (90 degrees Fahrenheit) makes this material especially appropriate for storing low grade solar heat for later release in space heating applications. In some application the material is incorporated into thermal tiles that are placed in an attic space while in other applications the salt is incorporated into cells surrounded by solar–heated water. The phase change allows a substantial reduction in the mass of the material required for effective heat storage (83 calories per gram stored across the phase change, versus one calorie per gram per degree Celsius using only water), with the further advantage of a consistency of temperature as long as sufficient material in the appropriate phase is available

[woodbowl]

I'm interested in storing heat in a super insulated tank as well. If heat can be reasonably stored to use in heating a home, why can't it be used for cooling also? How much temp does it take to activate an evaporator simular to camper refrigerators? Can it be used to lower temps in a home as an a/c?

It's hot here in Florida, real hot! You don't dare take a drink out of the water hose untill you let it run a while or you will have scalded lips. It's hot enough almost everywhere in North America during the summer to to store some heat.  Whatever the source of heat, wood, sun or alternative fuels, it seems wastefull to know that a lot of it  just goes up the pipe when mabe you could have tweeked some more btu's out of it.

[stonebroke]

masonry houses work real well in this application.

Stonebroke

[jdtuttle]

I'm a building inspector in NY & there are two homes being built now that have wood boilers for heat. They arn't the typical outdoor smoke polluting type. They have a fire chamber in the center of a water jacket that holds 1400 gals. of water. They are built inside a separate shed that has room for wood storage. The thing I like about these boilers is you fire it once a day in the winter. There are blowers in the fire box that help it burn hot & clean for 3 to 4 hours and your set for the day or up to a week in the summer. Looking forward to seeing how they work this winter. There is a sawmill near hear that has been using this system to heat their mill,kilns, and a couple homes. Theirs is larger & fires all day because of the demands. But if you have the fuel it's a great alternative. 
jim

[Radar67]

What are the brands Jim?

[Michigan Mike]

The wife and I went on the solar home tour here in lower michigan last fall.The one house that I was most interested in had a conventional poured basement insulated onthe outside of the poured walls. They then filled the basement with I belive sand with pipes running though it.  They had three different types of piping as they were not sure how the different types would hold up over the years. After the basement was filled it was capped with concrete. The solar collectors start heating the sand mass just about this time of the year. This gives heat just about for the entire winter. The house also had a masonary wood heater the kind that has the convoluted flue. The story was that the heater was seldom used until mid to late spring.

[WH_Conley]

I can only speak for one brand, that's all I have had. The  Hicks water stove that I have has 750 gal capacity. The heating of water and heating of home are 2 seperate circuits, for lack of a better term. I have seen water in a container setting on top of the stove freeze while the water temp in the stove was 180 degrees. I have fired the stove up and let it run several times to get the temp up and then let it go out for a couple of days. Guess this would be a type of thermal storage.

[RSteiner]

Years ago there was an outdoor wood fired heating system called a Hasa.  A friend of mine built one about 3 years ago to heat his house.  The firebox was surrounded with a fine washed sand.  The sand was at least a foot think on the sides and over 3 feet thick on top.  I believe the top on the fire box was 1/4 steel plate with angle iron reinfourcements to hold the weight.

Buried in the sand was a large grid of copper tubing that took the heat from the sand and was circulated throughout his house.  The idea was to have a very hot fire which heated the sand.  There was a lot of insulation around the outside of the whole structure to keep every thing hot. 

He was also talking about using different heat storing materials to improve the length of time between burns.  I don't think it was as efficient as a woodstove in the house.  The only down side was you had to go outside to load the stove and he did not have a woodshed near the Hasa so he had to deal with snow and ice covering the wood pile all winter.

I think one of the heat storage materials he was thinking of trying was parafin.

Randy

[Don_Papenburg]

Is this Glaubers salt  a corrosive ?   Like rock salt?

[jdtuttle]

Radar,
They are manufacturerd by Switzer's from Dundee NY. They are all custom built and have output ratings from 75,000 to 2,000,000 BTU. With the price of fuel soaring and no end in site I'm looking pretty hard at alternative fuels again.
jim

[Dodgy Loner]

Is this Glaubers salt  a corrosive ?   Like rock salt?

No.  Rock salt is sodium chloride.  Glauber's salt is sodium sulfate pentahydrate.  It is stable and non-corrosive.  Glauber's salt

[JSNH]

I had a Dumont boiler with a 2,500 gallon water tank. The tank had 2,000 gallons in it and it was sealed the extra 500 gallon volume was for expansion. I cycled it between 125 degrees and 185 degrees. 185-125=60*2000gal*7.5 pounds per gal=900,000 BTU's stored. I heated the house and all the hot water for the last 17 years with it. I would run it every day when the temps were below freezing and every other day when the temp was near freezing. I would feed it for 6 hours to store the 900k BTU's. It worked well and you burned somewhat according to your schedule.

I replaced it this past winter with a central boiler outside furnace. The Dumont boiler was about burnt out and no parts were available I would have to make my own.

It was a hard choice but I made the right one for me. No wood in the house now. No noise no drafts in the house. I burn maybe a bit more (20%) since this winter I burned what I had put up for the old system but I keep the house warmer now.

I have slabs and junk wood available plus I don't need to split as much so I can burn a lower quality of wood for most of the season but burn really good wood in the dead of winter. It is also much less time stoking the fire and that gives me more time with the family.

If you are putting in a highly efficient wood boiler you can't beat the heat storage of water. I moved on not because it did not work but the outdoor boiler works better for me due to location and fuel availability.

[JSNH]

My neighbor has a very large thermal solar collector. It is the evacuated tube style.
I   would estimate he has 120 collector tubes. Most domestic hot water systems have 20-30. He is using the heat for hot water and heating the house. The collector is at an ideal angle for winter to reduce over heating in the summer. He built his own tank that was about 700 gallons. It was welded stainless steel but it leaked. I helped him remove it on friday night with my plasma cutter. In 5 hours we removed the old tank and installed the new one. I was skeptical of the tank, it fit down the stairs into the basement coiled up. It was a 900 gallon tank in a box, like ups deleivered. The tank was made by some company in PA called SSTS. I never saw one like it before. It was light weight sheet metal with a bonded in insulated liner lined with a rubber membrane. It went together pretty easy and did not leak. How it will stand the test of time  I don't know but if you  are looking for heat storage do a web search on SSTS thermal storage tanks. It is something else out there you can at least be aware of.

[Engineer]

I have a client who has just built a house an hour's drive north of me.  When I went into his basement to talk to him last winter, he had two, 500 gallon propane tanks stuffed in the basement and he was in the processs of installing a wood furnace in the basement.  I guess I looked confused, 'cause he explained to be that the propane tanks were empty surplus tanks, and that he was going to hook them up and super-insulate them to provide 1000 gallons of stored hot water for his heat and domestic water. 

So I'm reading through this thread and I realized that I could do the same type of thing, my Central Boiler system has a 380+/- gallon capacity but I could easily bury a surplus 1000 gallon propane tank next to the boiler, insulate it well, and run it through a second zone on the boiler.  That way I'd have 1300 gallons of 180-degree water circulating and I would only have to feed my boiler every other day in the winter, and maybe once a week in the summer.   The past several weeks I have been feeding my wood boiler on average every 48-60 hours and that's to heat domestic hot water for a family of seven.  The kids have a small wading pool and they have taken to filling the pool up with cold water and then turning the hot water spigot on (I have a HW spigot outside the house for washing car, etc.) for a few minutes to take the chill off the cold well water.

[RSteiner]

I hope there is a heat exchanger for the domestic hot water.  I don't know what kind of residue is left in an old propane tank, I'm pretty sure I would not want water from a tank like that contacting my body.

The thermal storage idea sounds good.

Randy